1. Field of the Disclosure
The present invention relates generally to Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) communication systems, and more particularly to a system and method for reducing collisions in a CSMA/CA context.
2. Description of the Related Art
Multiple access communication systems are used any time more than two stations utilize a common medium for communication. There are many types of multiple access schemes; for example, some multiple access schemes include frequency division multiple access, time division multiple access, code division multiple access, and carrier sense multiple access (CSMA) schemes, such as CSMA with collision detection (CSMA/CD), and CSMA with collision avoidance (CSMA/CA).
CSMA schemes typically require a station that desires to use the medium to communicate to attempt to detect (to “sense”) whether another station is currently using the medium. If another station (a “carrier”) is sensed, the station will typically wait for the other station's communication to finish before attempting to communicate on the medium.
However, if for one reason or another (e.g., if multiple stations were waiting for another station's transmission to finish to attempt to transmit using the medium) multiple stations attempt to transmit on the medium simultaneously, then a collision occurs, and it is possible that neither attempt to communicate will be successful. Thus, CSMA/CD and CSMA/CA have been developed as refinements of the basic CSMA concept in order to reduce the impact of and/or avoid collisions; one or the other may be more appropriate in various contexts, e.g., depending on the type of medium.
As one example, the 802.11 protocol (WLAN) for wireless communication, also referred to as WiFi, is designed as a CSMA/CA system. Despite the collision avoidance techniques built into the CSMA/CA system, collisions can still occur relatively easily with the WiFi contention process. Furthermore, as the number of stations contending for medium access at a given time increases, so does the probability of a collision. In addition, due to the wireless nature of the medium in WiFi, there is no straightforward way to tell whether packet collisions happened at a receiver, even for a receiver itself. Accordingly, improvements in the field would be desirable.